Search Results (6,389)

The present study explores the production of metallized titanomagnetite briquettes, with a view to addressing two key issues. Firstly, it seeks to address the growing shortage of high-quality iron-bearing raw materials. Secondly, it looks at how to meet the increasingly stringent environmental constraints. The conventional blast-furnace treatment of titanomagnetite is hindered by the formation of refractory Ti-rich slags. It is hereby proposed that a single-cycle briquetting process in conjunction with a thermal reduction route should be utilized. This approach enables precise regulation of the Fe/flux ratio. Experiments were conducted on a low-grade titanomagnetite concentrate (68.5% Fe) from the Pervouralsk deposit (Russia). Cylindrical briquettes (D 15–20 mm, h 8–10 mm) were subjected to a pressure of 300 MPa during the pressing process, with the utilization of diverse binders comprising rubber cement, CaO, graphite + water, and basic oxygen-furnace (BOF) slag + sodium silicate. Following an oxidative pre-heating process at 1300 °C for two hours, followed by a gas-based reduction process at 1050 °C for three hours, with a CO/N₂ ratio of 90/10, the products demonstrated an oxidation rate of 85–95% and a cold compression strength of 16–80 MPa. The highest observed strength (80 MPa) was obtained with a binder comprising CaO·MgO·2SiO₂ (diopside/merwinite), which forms a low-viscosity melt, fills 90% of pores and crystallizes as acicular Mg-SFCA-I during cooling. Conversely, the CaO·TiO₂ and FeO·TiO₂ + Fe₃C associations yield brittle structures and a maximum strength of 16 MPa. The optimum briquette (0.55% CaO, D/H = 20/10 mm) exhibited a 95.7% metallization degree, a compressive strength of 48.9 MPa, and dimensional changes within acceptable limits, thus fulfilling the requirements for electric arc furnace feedstock. Further research is required in the form of a full Life Cycle Assessment and pilot-scale testing. However, the results obtained thus far confirm that titanomagnetite briquettes with a binder consisting of CaO, MgO and SiO₂ are a promising alternative to pellets for low-carbon steelmaking. Full article

In this paper, a strategy is proposed based on the microstructuring of GaAs substrates by photolithography combined with nanostructuring by electrochemical etching for the purposes of obtaining GaAs nanowire domains in selected regions of the substrate. The micropatterning is based on previously obtained knowledge about the mechanisms of pore growth in GaAs substrates during anodization. According to previous findings, crystallographically oriented pores, or “crysto pores,” grow along specific crystallographic directions within the GaAs substrates, with preferential propagation along the <111>B direction. Taking advantage of this feature, it is proposed to pattern the (111)B surface by photolithography and to, subsequently, apply anodization in an HNO₃ electrolyte. It is shown that the areas of the GaAs substrate under the photoresist mask are protected against porosification due to the growth of pores perpendicular to the surface of the substrates in such a configuration. Pores overlapping under adjusted electrochemical etching conditions results in the formation of GaAs nanowire arrays in the substrate regions not covered by photoresist. Thermal annealing conditions in an argon atmosphere with a low oxygen concentration were developed for the selective oxidation of GaAs nanowires, thus producing a wide-bandgap Ga₂O₃ nanowire pattern on the GaAs substrate. It is shown that the morphology of nanowires can be controlled by adjusting the electrochemical parameters. Smooth-walled nanowire arrays were obtained under specific conditions, while perforated and wall-modulated nanowires were formed when crystallographic pores intersected at a higher applied anodizing potential. Full article

Amyloid fibrillization represents an effective strategy for extending and enhancing protein function, particularly for the delivery of hydrophobic active substances. In this study, oat globulin (OG) and its fibrils were complexed with quercetin (Que) to construct the delivery system, and ultrasonic pretreatment was applied during fibril preparation to explore the promoter of complex formation. The results demonstrated that complexation with Que induced a dose-dependent static quenching of the intrinsic fluorescence of the protein/fibrils, with hydrophobic interactions and tryptophan residues being the primary interaction forces and the main fluorescence quenching groups, respectively. In comparison, OG fibrils prepared with ultrasound pretreatment (UOGF) exhibited the strongest encapsulation and loading capacity for Que, ranging from 97.16% at a mass ratio of 200:1 to 42.48% at a ratio of 25:1. Subsequently, complexes were prepared with a ratio of 50:1. Structural analysis revealed that Que primarily interacts with the protein/fibril carriers through hydrogen bonds and hydrophobic interactions, inducing structural changes and ultimately being encapsulated in an amorphous form within the composite material. Additionally, Que promoted the mutual aggregation and cross-linking of protein/fibril units, leading to increased hydrodynamic diameter and zeta-potential. Moreover, UOGF-Que showed the greatest improvement in the thermal stability and the photostability of Que, and enhancing the bioaccessibility. These findings provide valuable insights into using ultrasound as an auxiliary measure for fibril self-assembly to enhance the application potential of fibrils, especially the delivery of hydrophobic functional substances. Full article

In the present study, we have developed a series of compounds [M(tcm)₂(bix)₄]_n [where M = Co (1), Ni (2), and Cu (3)] using tricyanomethanide (tcm) and 1,4-bis(imidazol-1-ylmethyl)benzene (bix) ligands. The compounds were characterized by elemental analysis, PXRD, FT-IR and single-crystal X-ray crystallography. Single-crystal X-ray investigation of compounds 1, 2, and 3 shows the formation of the porous 2D structure. These 2D structures are further stacked to create a 3D network in the crystallographic space. All the compounds are thermally stable up to 300 °C, as revealed by the TGA. Hirshfeld surface analysis was carried out, and it reveals the existence of short intermolecular interactions between the layers. Full article

Efficient development of karst geothermal resources relies on the accurate identification of thermophysical and hydrogeological parameters. In this paper, the integrated wellbore–reservoir model of fluid and heat transport is applied to identify hydrothermal parameters of the karst geothermal system in Tianjin, China, based on multi-type field test data. A natural state model is conducted by fitting steady-state borehole temperature measurement results to identify formation thermal conductivity, while reservoir permeability is determined via the Gauss–Marquardt–Levenberg optimization algorithm based on dynamic temperature and pressure data from pumping tests. The parameter identification results indicate a reservoir permeability of 5.25 × 10⁻¹⁴ m² and a corrected bottom-hole temperature of 109 °C. Subsequently, productivity optimization for actual heating demands (1.33 × 10⁵ m²) yields an optimal heat extraction efficiency of 6.17 MW, with a flow rate of 80 m³/h, an injection well perforated length of 388 m, and an injection temperature of 30 °C. Additionally, addressing reservoir heterogeneity, the study finds that high-permeability zones between wells significantly shorten the safe operation duration of geothermal doublets, and reducing flow rate can mitigate thermal breakthrough risk to a certain extent. Full article

The article presents a numerical model of a high-temperature superconducting (HTS) transformer rated at 13.8 kVA, equipped with windings made of 2G ReBCO tapes. The model was developed to analyze the coupled electromagnetic and thermal phenomena occurring during the inrush current period of transformer energization. It describes the dynamic processes of critical current exceedance, resistive zone formation, and local temperature rise within the superconducting tape structure under realistic operating conditions. The geometry of the ReBCO tape is represented with its active superconducting layer and metallic stabilizer layers. Temperature-dependent material properties of each layer, such as electrical resistivity, thermal conductivity, and specific heat capacity, are incorporated into the model. This approach enables a detailed analysis of the temperature distribution across all layers of the superconducting tape. The results indicate that the highest thermal stress occurs during the first inrush current peak, whose amplitude exceeds the critical current of the winding. At this stage, a distinct temperature rise is observed in the stabilizer layers, followed by gradual cooling in subsequent cycles of operation. The simulated current and temperature waveforms show good agreement with experimental measurements performed on a liquid-nitrogen-cooled transformer prototype. The developed model enables quantitative evaluation of local overheating risks, analysis of Joule loss distribution, and assessment of the influence of supply parameters and circuit impedance on the thermal stability of the system. Its application supports the optimization of HTS transformer design and provides valuable insight into the reliability of superconducting windings under transient inrush current conditions. Full article

A nanostructured Al₂Fe₃Si₃ composite has been synthesized by high-energy ball milling followed by spark plasma sintering. Formations of oxides and FeSi or Al₂Fe₃Si₄ phases in nanometer-size scales were observed in addition to the matrix Al₂Fe₃Si₃ phase. Because of enhanced phonon scattering, the materials show low lattice thermal conductivities such as ~5 W/mK at the minimum. Full article

Snow construction plays a crucial role in military operations in cold regions, providing tactical fortifications, thermal insulation, and emergency infrastructure in environments where conventional building materials are scarce or require extensive infrastructure for support. Current snow construction methods, including manual piling and compaction, are labor-intensive and inconsistent, limiting their use in large-scale or time-sensitive operations. This study explores the feasibility of adapting a compressed earth block (CEB) machine to produce compressed snow blocks (CSBs) as modular, uniform building units for cold-region applications. Using an AECT Impact 2001A hydraulic press, naturally occurring snow was processed with a snowblower and compacted at maximum operating pressure (i.e., 20,684 kPa) to evaluate block formation, dimensional consistency, and density. The machine successfully produced relatively consistent CSBs, but the initial 3–4 blocks following block height adjustment were generally unsuccessful (e.g., incorrect block height or collapsed/broke) while the machine reached its steady state cyclic condition. These blocks were discarded and excluded from the dataset. The successful CSBs had mean block heights of 7.76 ± 0.56 cm and densities comparable to ice (i.e., 0.83 g/cm³). Variations in block height and mass may be attributed to manual snow loading and minor material impurities. While the dataset is limited, the results warrant further investigation into this technology, particularly regarding CSB strength (i.e., hardness and compressive strength) and performance under variable snow and environmental conditions. Mechanized snow compaction using existing CEB technology is technically feasible and capable of producing uniform, structurally stable CSBs but requires further investigation and modifications to reach its full potential. With design improvements such as automated snow feeding, cold-resistant components, and system winterization, this approach could enable scalable CSB production for rapid, on-site construction of snow-based structures in Arctic environments, supporting the military and civilian needs. Full article

This study provides the first comprehensive characterization and classification of organic microfacies within the globally significant Jurassic hydrocarbon source rocks of Iraqi Kurdistan. This study aims to resolve the knowledge gap in the Jurassic source rocks of northern Iraq by establishing the first organic microfacies classification scheme, utilizing an integrated petrographic and geochemical approach to reconstruct the regional paleoenvironmental evolution and confirm the source rock’s petroleum potential. The Middle–Late Jurassic Sargelu, Naokelekan, and Barsarin formations were investigated using samples from the Mangesh-1 and Sheikhan-8 wells. Using cluster analysis, we identified five distinct organic microfacies (A–E). Microfacies A (highly laminated bituminite), B (laminated/groundmass bituminite), C (laminated rock/lamalginite), and D (massive organic-matter-rich) show the highest hydrocarbon generation potential. The findings reveal a clear paleoenvironmental evolution: the Sargelu Formation was deposited in anoxic open marine conditions (microfacies C, D); the Naokelekan Formation represents a progressively restricted silled basin with intense anoxia leading to condensed sections dominated by microfacies A, which shows the highest source rock potential; and the Barsarin Formation reflects increasing restriction and hypersalinity, showing diverse microfacies (B, C, D, E) that captured variations in marine productivity and terrigenous influx. Principal component analysis (PCA) quantitatively modeled these paleoenvironmental gradients, aligning the distinct organic microfacies and their transitions with conceptual basin models. Geochemical analysis confirms that the organic matter is rich, predominantly Type II kerogen, and thermally mature, falling within the oil window. The presence of solid bitumen, both in situ and as evidence of migration (microfacies E), confirms effective hydrocarbon generation and movement. This integrated approach confirms the significant hydrocarbon potential of these Jurassic successions and highlights the critical role of specific organic microfacies in the region’s petroleum system, providing crucial guidance for future hydrocarbon exploration in northern Iraq. Full article

Kazakhstan’s asbestos industry produces over 3 million tons of waste annually. The primary component of asbestos ore waste (AOW) is magnesium rich minerals. In this study, the extraction of magnesium from AOW with nitric acid (HNO₃) was for the first time systematically studied. A series of experiments were conducted to optimize acid concentration (300–600 g/L), leaching temperature (55–95 °C), leaching time (60–180 min), solid-to-liquid ratio (1:3–1:7), and particle size, with the overall goal of maximizing magnesium extraction and cost efficiency. Our results provide dependence of magnesium extraction in the order of acid concentration  >  temperature  >  time  >  solid-to-liquid ratio, while particle size was found to be negligible. The cost-efficiency optimization demonstrated the positive impact of the relatively low acid concentrations (< 450 g/L) and temperatures between 65 and 85 °C, while the Protodyakonov model validated a linear dependence of the extraction rate on temperature and acid concentration. Our model demonstrates that extraction efficiencies of up to 90% can be achieved while reducing reagent use and lowering the overall cost of magnesium production. Leaching of magnesium by HNO₃ also opens a pathway to a closed-cycle process, due to the formation of magnesium nitrate. The thermal decomposition of Mg(NO₃)₂ provides valuable products such as MgO and NO₂ reused in HNO₃ regeneration for subsequent cycles. The proposed model predicts magnesium extraction from asbestos ore depending on leaching parameters with reasonable accuracy. Full article

Polyvinyl chloride (PVC), owing to its excellent electrical properties and low cost, is widely applied in the inner insulation and outer sheath of cables. To achieve early fault warning based on characteristic gases, this study integrates experimental testing with molecular simulations to systematically reveal the decomposition and gas generation characteristics of different PVC layers under electrical and thermal stresses. The results indicate that inner-layer PVC under electrical stress predominantly generates small-molecule olefins and halogenated hydrocarbons, while outer-layer PVC during thermal decomposition mainly produces hydrogen chloride, alkanes, and fragments of plasticizers. The surrounding atmosphere significantly regulates the gas generation pathways: air promotes the formation of CO₂ and H₂O, whereas electrical discharges accelerate the release of unsaturated hydrocarbons such as acetylene. By employing TG-FTIR, ReaxFF molecular dynamics, and DFT spectral calculations, a normalized infrared spectral library covering typical products was established and combined with the non-negative least squares method to realize quantitative deconvolution of mixed gases. Ultimately, a diagnostic system was constructed based on the concentration ratios of characteristic gases, which can effectively distinguish the failure modes of inner and outer PVC layers as well as different stress types. This provides a feasible approach for early detection of cable faults and supports intelligent maintenance strategies. Full article

In light of frequently occurring wellbore instability such as wellbore collapse and sand production that often occur in drilling and the completion of shale oil and gas development, we propose one-run shape memory thermosensitive screen technology that can expand spontaneously at a specific temperature to help strengthen the formation. Based on the theory of thermal expansion and large deformation of shape memory materials, the expansion process of the thermosensitive screen is calculated by the finite element method. After expanding to the wellbore wall, the effects of the screen squeezing force on the formation production parameters are evaluated theoretically. The analysis shows that the radial compressive stress of the thermosensitive screen decreases with the increase in the radial distance, but as the original outer diameter of the thermosensitive screen is greater than the wellbore diameter, it can provide extrusion force for the wellbore wall. According to the in situ stress model, the extrusion force after the screen contacts the wellbore can effectively improve the stress distribution near the wellbore and reduce the impact of sand production caused by formation instability. Moreover, in shale oil and gas completion, it can effectively increase the bottom hole flowing pressure and drawdown pressure. Full article

This paper investigates the abnormal combustion behavior—specifically knock and pre-ignition—of a hydrogen direct-injection (H₂-DI) engine operated under stoichiometric conditions. Two different cylinder head configurations with central and lateral injector placement are analyzed using thermodynamic measurements, CFD simulations, and the optical diagnostic system VISIOLution^®. The results show that combustion stability and knock tendency are significantly influenced by injector positioning, injection pressure, and ignition timing. Controlled mixture formation and high turbulence during the compression phase are key to achieving both high power density and thermal efficiency in hydrogen-fueled engines. Full article

The growing need for effective antimicrobial polymeric materials has prompted extensive development of functional chitosan derivatives with enhanced physicochemical and biological properties. In this work, the conjugates of chitosan with 4-anisaldehyde (ChT-AA) were synthesised through Schiff base formation at various molar ratios and characterised using FT-IR, ¹H NMR, and thermal analysis techniques (TGA/DSC). The spectral data confirmed the successful formation of imine (C=N) linkages and the incorporation of aromatic anisaldehyde fragments into the chitosan structure. Thermal analysis demonstrated increased stability and a higher glass transition temperature for ChT-AA compared with native chitosan, indicating reduced polymer chain mobility and enhanced structural rigidity. Viscoelastic gels based on the synthesised ChT-AA (1:3) and methylcellulose were prepared and evaluated for their rheological properties and antimicrobial performance. Rheological studies revealed non-Newtonian shear-thinning behaviour of these gels with pronounced thixotropy, confirming reversible network recovery after shear deformation. Antimicrobial evaluation of chitosan, its 4-anisaldehyde conjugate (ChT–AA, 1:3), and free 4-anisaldehyde revealed distinct activity patterns. The gels showed no inhibition in the disk diffusion assay, likely due to limited diffusion of the active components. In liquid media, both ChT and ChT–AA exhibited identical minimum inhibitory concentrations (MICs) against E. coli (0.313 mg/mL) and C. albicans (1.250 mg/mL), whereas ChT–AA showed two-fold stronger activity against S. aureus (0.313 mg/mL vs. 0.625 mg/mL for ChT). Free 4-anisaldehyde was most active against S. aureus (MIC = 0.175 mg/mL) but less effective against the other strains, confirming its narrower spectrum. These results indicate moderate antimicrobial efficacy in solution but limited activity in gel form due to restricted diffusion. Full article

Fractured lost circulation remains a major drilling challenge due to low compatibility between conventional plugging materials and fractures. By utilizing thermosetting resin emulsification and high-temperature crosslinking coalescence, this study developed a temperature-activated nanomaterial enhanced liquid–solid phase transition plugging emulsion. The system adapts to varying fracture apertures, forming plugging particles with a broad size distribution and high strength upon thermal activation. The structural characteristics, mechanical properties, and fracture-plugging performance of the plugging particles were systematically investigated. Results demonstrate that the optimized system, comprising 8 wt.% emulsifier, 0.16 wt.% dispersant, 0.4 wt.% crosslinker, 0.4 wt.% viscosifier, 70 wt.% distilled water, and 2 wt.% nano-silica (all percentages relative to epoxy resin content), can produce particles with a size of 1–5 mm at formation temperatures of 80–120 °C. After 16 h of thermal aging at 180 °C, the particles exhibited excellent thermal stability and compressive strength, with D(90) degradation rates of 3.07–5.41%, and mass loss of 0.63–3.40% under 60 MPa. The system exhibits excellent injectability and drilling fluid compatibility, forming rough-surfaced particles for stable bridging. Microscopic analysis confirmed full curing in 140–180 min. Notably, it sealed 1–5 mm fractures with 10 MPa pressure, enabling adaptive plugging for unknown fracture apertures. Full article